llvm-project/compiler-rt/lib/tsan/rtl/tsan_rtl.cc

//===-- tsan_rtl.cc -------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of ThreadSanitizer (TSan), a race detector.
//
// Main file (entry points) for the TSan run-time.
//===----------------------------------------------------------------------===//

#include "sanitizer_common/sanitizer_atomic.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_libc.h"
#include "sanitizer_common/sanitizer_stackdepot.h"
#include "sanitizer_common/sanitizer_placement_new.h"
#include "sanitizer_common/sanitizer_symbolizer.h"
#include "tsan_defs.h"
#include "tsan_platform.h"
#include "tsan_rtl.h"
#include "tsan_mman.h"
#include "tsan_suppressions.h"
#include "tsan_symbolize.h"

volatile int __tsan_resumed = 0;

extern "C" void __tsan_resume() {
  __tsan_resumed = 1;
}

namespace __tsan {

#ifndef TSAN_GO
THREADLOCAL char cur_thread_placeholder[sizeof(ThreadState)] ALIGNED(64);
#endif
static char ctx_placeholder[sizeof(Context)] ALIGNED(64);

// Can be overriden by a front-end.
#ifdef TSAN_EXTERNAL_HOOKS
bool OnFinalize(bool failed);
#else
bool WEAK OnFinalize(bool failed) {
  return failed;
}
#endif

static Context *ctx;
Context *CTX() {
  return ctx;
}

static char thread_registry_placeholder[sizeof(ThreadRegistry)];

static ThreadContextBase *CreateThreadContext(u32 tid) {
  // Map thread trace when context is created.
  MapThreadTrace(GetThreadTrace(tid), TraceSize() * sizeof(Event));
  MapThreadTrace(GetThreadTraceHeader(tid), sizeof(Trace));
  new(ThreadTrace(tid)) Trace();
  void *mem = internal_alloc(MBlockThreadContex, sizeof(ThreadContext));
  return new(mem) ThreadContext(tid);
}

#ifndef TSAN_GO
static const u32 kThreadQuarantineSize = 16;
#else
static const u32 kThreadQuarantineSize = 64;
#endif

Context::Context()
  : initialized()
  , report_mtx(MutexTypeReport, StatMtxReport)
  , nreported()
  , nmissed_expected()
  , thread_registry(new(thread_registry_placeholder) ThreadRegistry(
      CreateThreadContext, kMaxTid, kThreadQuarantineSize))
  , racy_stacks(MBlockRacyStacks)
  , racy_addresses(MBlockRacyAddresses)
  , fired_suppressions(8) {
}

// The objects are allocated in TLS, so one may rely on zero-initialization.
ThreadState::ThreadState(Context *ctx, int tid, int unique_id, u64 epoch,
                         uptr stk_addr, uptr stk_size,
                         uptr tls_addr, uptr tls_size)
  : fast_state(tid, epoch)
  // Do not touch these, rely on zero initialization,
  // they may be accessed before the ctor.
  // , ignore_reads_and_writes()
  // , in_rtl()
  , shadow_stack_pos(&shadow_stack[0])
#ifndef TSAN_GO
  , jmp_bufs(MBlockJmpBuf)
#endif
  , tid(tid)
  , unique_id(unique_id)
  , stk_addr(stk_addr)
  , stk_size(stk_size)
  , tls_addr(tls_addr)
  , tls_size(tls_size) {
}

static void MemoryProfiler(Context *ctx, fd_t fd, int i) {
  uptr n_threads;
  uptr n_running_threads;
  ctx->thread_registry->GetNumberOfThreads(&n_threads, &n_running_threads);
  InternalScopedBuffer<char> buf(4096);
  internal_snprintf(buf.data(), buf.size(), "%d: nthr=%d nlive=%d\n",
      i, n_threads, n_running_threads);
  internal_write(fd, buf.data(), internal_strlen(buf.data()));
  WriteMemoryProfile(buf.data(), buf.size());
  internal_write(fd, buf.data(), internal_strlen(buf.data()));
}

static void BackgroundThread(void *arg) {
  ScopedInRtl in_rtl;
  Context *ctx = CTX();
  const u64 kMs2Ns = 1000 * 1000;

  fd_t mprof_fd = kInvalidFd;
  if (flags()->profile_memory && flags()->profile_memory[0]) {
    InternalScopedBuffer<char> filename(4096);
    internal_snprintf(filename.data(), filename.size(), "%s.%d",
        flags()->profile_memory, (int)internal_getpid());
    uptr openrv = OpenFile(filename.data(), true);
    if (internal_iserror(openrv)) {
      Printf("ThreadSanitizer: failed to open memory profile file '%s'\n",
          &filename[0]);
    } else {
      mprof_fd = openrv;
    }
  }

  u64 last_flush = NanoTime();
  uptr last_rss = 0;
  for (int i = 0; ; i++) {
    SleepForSeconds(1);
    u64 now = NanoTime();

    // Flush memory if requested.
    if (flags()->flush_memory_ms > 0) {
      if (last_flush + flags()->flush_memory_ms * kMs2Ns < now) {
        if (flags()->verbosity > 0)
          Printf("ThreadSanitizer: periodic memory flush\n");
        FlushShadowMemory();
        last_flush = NanoTime();
      }
    }
    if (flags()->memory_limit_mb > 0) {
      uptr rss = GetRSS();
      uptr limit = uptr(flags()->memory_limit_mb) << 20;
      if (flags()->verbosity > 0) {
        Printf("ThreadSanitizer: memory flush check"
               " RSS=%llu LAST=%llu LIMIT=%llu\n",
               (u64)rss>>20, (u64)last_rss>>20, (u64)limit>>20);
      }
      if (2 * rss > limit + last_rss) {
        if (flags()->verbosity > 0)
          Printf("ThreadSanitizer: flushing memory due to RSS\n");
        FlushShadowMemory();
        rss = GetRSS();
        if (flags()->verbosity > 0)
          Printf("ThreadSanitizer: memory flushed RSS=%llu\n", (u64)rss>>20);
      }
      last_rss = rss;
    }

    // Write memory profile if requested.
    if (mprof_fd != kInvalidFd)
      MemoryProfiler(ctx, mprof_fd, i);

#ifndef TSAN_GO
    // Flush symbolizer cache if requested.
    if (flags()->flush_symbolizer_ms > 0) {
      u64 last = atomic_load(&ctx->last_symbolize_time_ns,
                             memory_order_relaxed);
      if (last != 0 && last + flags()->flush_symbolizer_ms * kMs2Ns < now) {
        Lock l(&ctx->report_mtx);
        SpinMutexLock l2(&CommonSanitizerReportMutex);
        SymbolizeFlush();
        atomic_store(&ctx->last_symbolize_time_ns, 0, memory_order_relaxed);
      }
    }
#endif
  }
}

void DontNeedShadowFor(uptr addr, uptr size) {
  uptr shadow_beg = MemToShadow(addr);
  uptr shadow_end = MemToShadow(addr + size);
  FlushUnneededShadowMemory(shadow_beg, shadow_end - shadow_beg);
}

void MapShadow(uptr addr, uptr size) {
  MmapFixedNoReserve(MemToShadow(addr), size * kShadowMultiplier);
}

void MapThreadTrace(uptr addr, uptr size) {
  DPrintf("#0: Mapping trace at %p-%p(0x%zx)\n", addr, addr + size, size);
  CHECK_GE(addr, kTraceMemBegin);
  CHECK_LE(addr + size, kTraceMemBegin + kTraceMemSize);
  if (addr != (uptr)MmapFixedNoReserve(addr, size)) {
    Printf("FATAL: ThreadSanitizer can not mmap thread trace\n");
    Die();
  }
}

void Initialize(ThreadState *thr) {
  // Thread safe because done before all threads exist.
  static bool is_initialized = false;
  if (is_initialized)
    return;
  is_initialized = true;
  SanitizerToolName = "ThreadSanitizer";
  // Install tool-specific callbacks in sanitizer_common.
  SetCheckFailedCallback(TsanCheckFailed);

  ScopedInRtl in_rtl;
#ifndef TSAN_GO
  InitializeAllocator();
#endif
  InitializeInterceptors();
  const char *env = InitializePlatform();
  InitializeMutex();
  InitializeDynamicAnnotations();
  ctx = new(ctx_placeholder) Context;
#ifndef TSAN_GO
  InitializeShadowMemory();
#endif
  InitializeFlags(&ctx->flags, env);
  // Setup correct file descriptor for error reports.
  if (internal_strcmp(flags()->log_path, "stdout") == 0)
    __sanitizer_set_report_fd(kStdoutFd);
  else if (internal_strcmp(flags()->log_path, "stderr") == 0)
    __sanitizer_set_report_fd(kStderrFd);
  else
    __sanitizer_set_report_path(flags()->log_path);
  InitializeSuppressions();
#ifndef TSAN_GO
  InitializeLibIgnore();
  // Initialize external symbolizer before internal threads are started.
  const char *external_symbolizer = flags()->external_symbolizer_path;
  bool symbolizer_started =
      getSymbolizer()->InitializeExternal(external_symbolizer);
  if (external_symbolizer != 0 && external_symbolizer[0] != '\0' &&
      !symbolizer_started) {
    Printf("Failed to start external symbolizer: '%s'\n",
           external_symbolizer);
    Die();
  }
#endif
  internal_start_thread(&BackgroundThread, 0);

  if (ctx->flags.verbosity)
    Printf("***** Running under ThreadSanitizer v2 (pid %d) *****\n",
           (int)internal_getpid());

  // Initialize thread 0.
  int tid = ThreadCreate(thr, 0, 0, true);
  CHECK_EQ(tid, 0);
  ThreadStart(thr, tid, internal_getpid());
  CHECK_EQ(thr->in_rtl, 1);
  ctx->initialized = true;

  if (flags()->stop_on_start) {
    Printf("ThreadSanitizer is suspended at startup (pid %d)."
           " Call __tsan_resume().\n",
           (int)internal_getpid());
    while (__tsan_resumed == 0) {}
  }
}

int Finalize(ThreadState *thr) {
  ScopedInRtl in_rtl;
  Context *ctx = __tsan::ctx;
  bool failed = false;

  if (flags()->atexit_sleep_ms > 0 && ThreadCount(thr) > 1)
    SleepForMillis(flags()->atexit_sleep_ms);

  // Wait for pending reports.
  ctx->report_mtx.Lock();
  CommonSanitizerReportMutex.Lock();
  CommonSanitizerReportMutex.Unlock();
  ctx->report_mtx.Unlock();

#ifndef TSAN_GO
  if (ctx->flags.verbosity)
    AllocatorPrintStats();
#endif

  ThreadFinalize(thr);

  if (ctx->nreported) {
    failed = true;
#ifndef TSAN_GO
    Printf("ThreadSanitizer: reported %d warnings\n", ctx->nreported);
#else
    Printf("Found %d data race(s)\n", ctx->nreported);
#endif
  }

  if (ctx->nmissed_expected) {
    failed = true;
    Printf("ThreadSanitizer: missed %d expected races\n",
        ctx->nmissed_expected);
  }

  if (flags()->print_suppressions)
    PrintMatchedSuppressions();
#ifndef TSAN_GO
  if (flags()->print_benign)
    PrintMatchedBenignRaces();
#endif

  failed = OnFinalize(failed);

  StatAggregate(ctx->stat, thr->stat);
  StatOutput(ctx->stat);
  return failed ? flags()->exitcode : 0;
}

#ifndef TSAN_GO
u32 CurrentStackId(ThreadState *thr, uptr pc) {
  if (thr->shadow_stack_pos == 0)  // May happen during bootstrap.
    return 0;
  if (pc) {
    thr->shadow_stack_pos[0] = pc;
    thr->shadow_stack_pos++;
  }
  u32 id = StackDepotPut(thr->shadow_stack,
                         thr->shadow_stack_pos - thr->shadow_stack);
  if (pc)
    thr->shadow_stack_pos--;
  return id;
}
#endif

void TraceSwitch(ThreadState *thr) {
  thr->nomalloc++;
  ScopedInRtl in_rtl;
  Trace *thr_trace = ThreadTrace(thr->tid);
  Lock l(&thr_trace->mtx);
  unsigned trace = (thr->fast_state.epoch() / kTracePartSize) % TraceParts();
  TraceHeader *hdr = &thr_trace->headers[trace];
  hdr->epoch0 = thr->fast_state.epoch();
  hdr->stack0.ObtainCurrent(thr, 0);
  hdr->mset0 = thr->mset;
  thr->nomalloc--;
}

Trace *ThreadTrace(int tid) {
  return (Trace*)GetThreadTraceHeader(tid);
}

uptr TraceTopPC(ThreadState *thr) {
  Event *events = (Event*)GetThreadTrace(thr->tid);
  uptr pc = events[thr->fast_state.GetTracePos()];
  return pc;
}

uptr TraceSize() {
  return (uptr)(1ull << (kTracePartSizeBits + flags()->history_size + 1));
}

uptr TraceParts() {
  return TraceSize() / kTracePartSize;
}

#ifndef TSAN_GO
extern "C" void __tsan_trace_switch() {
  TraceSwitch(cur_thread());
}

extern "C" void __tsan_report_race() {
  ReportRace(cur_thread());
}
#endif

ALWAYS_INLINE
Shadow LoadShadow(u64 *p) {
  u64 raw = atomic_load((atomic_uint64_t*)p, memory_order_relaxed);
  return Shadow(raw);
}

ALWAYS_INLINE
void StoreShadow(u64 *sp, u64 s) {
  atomic_store((atomic_uint64_t*)sp, s, memory_order_relaxed);
}

ALWAYS_INLINE
void StoreIfNotYetStored(u64 *sp, u64 *s) {
  StoreShadow(sp, *s);
  *s = 0;
}

static inline void HandleRace(ThreadState *thr, u64 *shadow_mem,
                              Shadow cur, Shadow old) {
  thr->racy_state[0] = cur.raw();
  thr->racy_state[1] = old.raw();
  thr->racy_shadow_addr = shadow_mem;
#ifndef TSAN_GO
  HACKY_CALL(__tsan_report_race);
#else
  ReportRace(thr);
#endif
}

static inline bool OldIsInSameSynchEpoch(Shadow old, ThreadState *thr) {
  return old.epoch() >= thr->fast_synch_epoch;
}

static inline bool HappensBefore(Shadow old, ThreadState *thr) {
  return thr->clock.get(old.TidWithIgnore()) >= old.epoch();
}

ALWAYS_INLINE USED
void MemoryAccessImpl(ThreadState *thr, uptr addr,
    int kAccessSizeLog, bool kAccessIsWrite, bool kIsAtomic,
    u64 *shadow_mem, Shadow cur) {
  StatInc(thr, StatMop);
  StatInc(thr, kAccessIsWrite ? StatMopWrite : StatMopRead);
  StatInc(thr, (StatType)(StatMop1 + kAccessSizeLog));

  // This potentially can live in an MMX/SSE scratch register.
  // The required intrinsics are:
  // __m128i _mm_move_epi64(__m128i*);
  // _mm_storel_epi64(u64*, __m128i);
  u64 store_word = cur.raw();

  // scan all the shadow values and dispatch to 4 categories:
  // same, replace, candidate and race (see comments below).
  // we consider only 3 cases regarding access sizes:
  // equal, intersect and not intersect. initially I considered
  // larger and smaller as well, it allowed to replace some
  // 'candidates' with 'same' or 'replace', but I think
  // it's just not worth it (performance- and complexity-wise).

  Shadow old(0);
  if (kShadowCnt == 1) {
    int idx = 0;
#include "tsan_update_shadow_word_inl.h"
  } else if (kShadowCnt == 2) {
    int idx = 0;
#include "tsan_update_shadow_word_inl.h"
    idx = 1;
#include "tsan_update_shadow_word_inl.h"
  } else if (kShadowCnt == 4) {
    int idx = 0;
#include "tsan_update_shadow_word_inl.h"
    idx = 1;
#include "tsan_update_shadow_word_inl.h"
    idx = 2;
#include "tsan_update_shadow_word_inl.h"
    idx = 3;
#include "tsan_update_shadow_word_inl.h"
  } else if (kShadowCnt == 8) {
    int idx = 0;
#include "tsan_update_shadow_word_inl.h"
    idx = 1;
#include "tsan_update_shadow_word_inl.h"
    idx = 2;
#include "tsan_update_shadow_word_inl.h"
    idx = 3;
#include "tsan_update_shadow_word_inl.h"
    idx = 4;
#include "tsan_update_shadow_word_inl.h"
    idx = 5;
#include "tsan_update_shadow_word_inl.h"
    idx = 6;
#include "tsan_update_shadow_word_inl.h"
    idx = 7;
#include "tsan_update_shadow_word_inl.h"
  } else {
    CHECK(false);
  }

  // we did not find any races and had already stored
  // the current access info, so we are done
  if (LIKELY(store_word == 0))
    return;
  // choose a random candidate slot and replace it
  StoreShadow(shadow_mem + (cur.epoch() % kShadowCnt), store_word);
  StatInc(thr, StatShadowReplace);
  return;
 RACE:
  HandleRace(thr, shadow_mem, cur, old);
  return;
}

void UnalignedMemoryAccess(ThreadState *thr, uptr pc, uptr addr,
    int size, bool kAccessIsWrite, bool kIsAtomic) {
  while (size) {
    int size1 = 1;
    int kAccessSizeLog = kSizeLog1;
    if (size >= 8 && (addr & ~7) == ((addr + 8) & ~7)) {
      size1 = 8;
      kAccessSizeLog = kSizeLog8;
    } else if (size >= 4 && (addr & ~7) == ((addr + 4) & ~7)) {
      size1 = 4;
      kAccessSizeLog = kSizeLog4;
    } else if (size >= 2 && (addr & ~7) == ((addr + 2) & ~7)) {
      size1 = 2;
      kAccessSizeLog = kSizeLog2;
    }
    MemoryAccess(thr, pc, addr, kAccessSizeLog, kAccessIsWrite, kIsAtomic);
    addr += size1;
    size -= size1;
  }
}

ALWAYS_INLINE USED
void MemoryAccess(ThreadState *thr, uptr pc, uptr addr,
    int kAccessSizeLog, bool kAccessIsWrite, bool kIsAtomic) {
  u64 *shadow_mem = (u64*)MemToShadow(addr);
  DPrintf2("#%d: MemoryAccess: @%p %p size=%d"
      " is_write=%d shadow_mem=%p {%zx, %zx, %zx, %zx}\n",
      (int)thr->fast_state.tid(), (void*)pc, (void*)addr,
      (int)(1 << kAccessSizeLog), kAccessIsWrite, shadow_mem,
      (uptr)shadow_mem[0], (uptr)shadow_mem[1],
      (uptr)shadow_mem[2], (uptr)shadow_mem[3]);
#if TSAN_DEBUG
  if (!IsAppMem(addr)) {
    Printf("Access to non app mem %zx\n", addr);
    DCHECK(IsAppMem(addr));
  }
  if (!IsShadowMem((uptr)shadow_mem)) {
    Printf("Bad shadow addr %p (%zx)\n", shadow_mem, addr);
    DCHECK(IsShadowMem((uptr)shadow_mem));
  }
#endif

  if (*shadow_mem == kShadowRodata) {
    // Access to .rodata section, no races here.
    // Measurements show that it can be 10-20% of all memory accesses.
    StatInc(thr, StatMop);
    StatInc(thr, kAccessIsWrite ? StatMopWrite : StatMopRead);
    StatInc(thr, (StatType)(StatMop1 + kAccessSizeLog));
    StatInc(thr, StatMopRodata);
    return;
  }

  FastState fast_state = thr->fast_state;
  if (fast_state.GetIgnoreBit())
    return;
  fast_state.IncrementEpoch();
  thr->fast_state = fast_state;
  Shadow cur(fast_state);
  cur.SetAddr0AndSizeLog(addr & 7, kAccessSizeLog);
  cur.SetWrite(kAccessIsWrite);
  cur.SetAtomic(kIsAtomic);

  // We must not store to the trace if we do not store to the shadow.
  // That is, this call must be moved somewhere below.
  TraceAddEvent(thr, fast_state, EventTypeMop, pc);

  MemoryAccessImpl(thr, addr, kAccessSizeLog, kAccessIsWrite, kIsAtomic,
      shadow_mem, cur);
}

static void MemoryRangeSet(ThreadState *thr, uptr pc, uptr addr, uptr size,
                           u64 val) {
  (void)thr;
  (void)pc;
  if (size == 0)
    return;
  // FIXME: fix me.
  uptr offset = addr % kShadowCell;
  if (offset) {
    offset = kShadowCell - offset;
    if (size <= offset)
      return;
    addr += offset;
    size -= offset;
  }
  DCHECK_EQ(addr % 8, 0);
  // If a user passes some insane arguments (memset(0)),
  // let it just crash as usual.
  if (!IsAppMem(addr) || !IsAppMem(addr + size - 1))
    return;
  // Don't want to touch lots of shadow memory.
  // If a program maps 10MB stack, there is no need reset the whole range.
  size = (size + (kShadowCell - 1)) & ~(kShadowCell - 1);
  // UnmapOrDie/MmapFixedNoReserve does not work on Windows,
  // so we do it only for C/C++.
  if (kGoMode || size < 64*1024) {
    u64 *p = (u64*)MemToShadow(addr);
    CHECK(IsShadowMem((uptr)p));
    CHECK(IsShadowMem((uptr)(p + size * kShadowCnt / kShadowCell - 1)));
    // FIXME: may overwrite a part outside the region
    for (uptr i = 0; i < size / kShadowCell * kShadowCnt;) {
      p[i++] = val;
      for (uptr j = 1; j < kShadowCnt; j++)
        p[i++] = 0;
    }
  } else {
    // The region is big, reset only beginning and end.
    const uptr kPageSize = 4096;
    u64 *begin = (u64*)MemToShadow(addr);
    u64 *end = begin + size / kShadowCell * kShadowCnt;
    u64 *p = begin;
    // Set at least first kPageSize/2 to page boundary.
    while ((p < begin + kPageSize / kShadowSize / 2) || ((uptr)p % kPageSize)) {
      *p++ = val;
      for (uptr j = 1; j < kShadowCnt; j++)
        *p++ = 0;
    }
    // Reset middle part.
    u64 *p1 = p;
    p = RoundDown(end, kPageSize);
    UnmapOrDie((void*)p1, (uptr)p - (uptr)p1);
    MmapFixedNoReserve((uptr)p1, (uptr)p - (uptr)p1);
    // Set the ending.
    while (p < end) {
      *p++ = val;
      for (uptr j = 1; j < kShadowCnt; j++)
        *p++ = 0;
    }
  }
}

void MemoryResetRange(ThreadState *thr, uptr pc, uptr addr, uptr size) {
  MemoryRangeSet(thr, pc, addr, size, 0);
}

void MemoryRangeFreed(ThreadState *thr, uptr pc, uptr addr, uptr size) {
  // Processing more than 1k (4k of shadow) is expensive,
  // can cause excessive memory consumption (user does not necessary touch
  // the whole range) and most likely unnecessary.
  if (size > 1024)
    size = 1024;
  CHECK_EQ(thr->is_freeing, false);
  thr->is_freeing = true;
  MemoryAccessRange(thr, pc, addr, size, true);
  thr->is_freeing = false;
  thr->fast_state.IncrementEpoch();
  TraceAddEvent(thr, thr->fast_state, EventTypeMop, pc);
  Shadow s(thr->fast_state);
  s.ClearIgnoreBit();
  s.MarkAsFreed();
  s.SetWrite(true);
  s.SetAddr0AndSizeLog(0, 3);
  MemoryRangeSet(thr, pc, addr, size, s.raw());
}

void MemoryRangeImitateWrite(ThreadState *thr, uptr pc, uptr addr, uptr size) {
  thr->fast_state.IncrementEpoch();
  TraceAddEvent(thr, thr->fast_state, EventTypeMop, pc);
  Shadow s(thr->fast_state);
  s.ClearIgnoreBit();
  s.SetWrite(true);
  s.SetAddr0AndSizeLog(0, 3);
  MemoryRangeSet(thr, pc, addr, size, s.raw());
}

ALWAYS_INLINE USED
void FuncEntry(ThreadState *thr, uptr pc) {
  DCHECK_EQ(thr->in_rtl, 0);
  StatInc(thr, StatFuncEnter);
  DPrintf2("#%d: FuncEntry %p\n", (int)thr->fast_state.tid(), (void*)pc);
  thr->fast_state.IncrementEpoch();
  TraceAddEvent(thr, thr->fast_state, EventTypeFuncEnter, pc);

  // Shadow stack maintenance can be replaced with
  // stack unwinding during trace switch (which presumably must be faster).
  DCHECK_GE(thr->shadow_stack_pos, &thr->shadow_stack[0]);
#ifndef TSAN_GO
  DCHECK_LT(thr->shadow_stack_pos, &thr->shadow_stack[kShadowStackSize]);
#else
  if (thr->shadow_stack_pos == thr->shadow_stack_end) {
    const int sz = thr->shadow_stack_end - thr->shadow_stack;
    const int newsz = 2 * sz;
    uptr *newstack = (uptr*)internal_alloc(MBlockShadowStack,
        newsz * sizeof(uptr));
    internal_memcpy(newstack, thr->shadow_stack, sz * sizeof(uptr));
    internal_free(thr->shadow_stack);
    thr->shadow_stack = newstack;
    thr->shadow_stack_pos = newstack + sz;
    thr->shadow_stack_end = newstack + newsz;
  }
#endif
  thr->shadow_stack_pos[0] = pc;
  thr->shadow_stack_pos++;
}

ALWAYS_INLINE USED
void FuncExit(ThreadState *thr) {
  DCHECK_EQ(thr->in_rtl, 0);
  StatInc(thr, StatFuncExit);
  DPrintf2("#%d: FuncExit\n", (int)thr->fast_state.tid());
  thr->fast_state.IncrementEpoch();
  TraceAddEvent(thr, thr->fast_state, EventTypeFuncExit, 0);

  DCHECK_GT(thr->shadow_stack_pos, &thr->shadow_stack[0]);
#ifndef TSAN_GO
  DCHECK_LT(thr->shadow_stack_pos, &thr->shadow_stack[kShadowStackSize]);
#endif
  thr->shadow_stack_pos--;
}

void ThreadIgnoreBegin(ThreadState *thr) {
  DPrintf("#%d: ThreadIgnoreBegin\n", thr->tid);
  thr->ignore_reads_and_writes++;
  CHECK_GT(thr->ignore_reads_and_writes, 0);
  thr->fast_state.SetIgnoreBit();
}

void ThreadIgnoreEnd(ThreadState *thr) {
  DPrintf("#%d: ThreadIgnoreEnd\n", thr->tid);
  thr->ignore_reads_and_writes--;
  CHECK_GE(thr->ignore_reads_and_writes, 0);
  if (thr->ignore_reads_and_writes == 0)
    thr->fast_state.ClearIgnoreBit();
}

void ThreadIgnoreSyncBegin(ThreadState *thr) {
  DPrintf("#%d: ThreadIgnoreSyncBegin\n", thr->tid);
  thr->ignore_sync++;
  CHECK_GT(thr->ignore_sync, 0);
}

void ThreadIgnoreSyncEnd(ThreadState *thr) {
  DPrintf("#%d: ThreadIgnoreSyncEnd\n", thr->tid);
  thr->ignore_sync--;
  CHECK_GE(thr->ignore_sync, 0);
}

bool MD5Hash::operator==(const MD5Hash &other) const {
  return hash[0] == other.hash[0] && hash[1] == other.hash[1];
}

#if TSAN_DEBUG
void build_consistency_debug() {}
#else
void build_consistency_release() {}
#endif

#if TSAN_COLLECT_STATS
void build_consistency_stats() {}
#else
void build_consistency_nostats() {}
#endif

#if TSAN_SHADOW_COUNT == 1
void build_consistency_shadow1() {}
#elif TSAN_SHADOW_COUNT == 2
void build_consistency_shadow2() {}
#elif TSAN_SHADOW_COUNT == 4
void build_consistency_shadow4() {}
#else
void build_consistency_shadow8() {}
#endif

}  // namespace __tsan

#ifndef TSAN_GO
// Must be included in this file to make sure everything is inlined.
#include "tsan_interface_inl.h"
#endif